BIOCHEMICAL REACTIONS 165 



sera and known negative cases. If it proves reliable, 

 it may then be used for diagnosis of unknown sera. 

 Known positive and negative controls should always 

 be used in performing the test, and titration of the 

 extract should frequently be carried out, as its strength 

 is not constant. A reaction is regarded as positive 

 when the number of drops is more than 1% in excess 

 of the control. 



For the test, a mixture of the suspected serum and 

 the dose of extract is made ; also a mixture of the sus- 

 pected serum and distilled water. The same thing is 

 done with normal serum. These mixtures are then 

 incubated for 2 hours at 37° C. In the case of a posi- 

 tive result the mixture of the patient's serum and 

 tumor or pancreas extract must have an increase of 

 more than 1% drops over the mixture of patient's 

 serum and water, and over the mixture of normal 

 serum and extract. 



The following table gives an example of a positive 

 result : 



Number of drops 

 Normal serum (control) 9 c.c. 1 : 20 dil. + 1 c.c. extract 



1 : 100 dil 59 



Normal serum (control) 9 c.c. 1:20 dil. + 1 c.c. aqua dest. 58 + 4 parts 

 Suspected cancer serum 9 c.c. 1 : 20 dil. + 1 c.c. extract 



1 : 100 dil 61 



Suspected cancer serum 9 c.c. 1 : 20 dil. -\- 1 c.c. aqua dest. 58 -|- 7 parts 



Different investigators working with the meio- 

 stagmin reaction give varying reports as to its relia- 



